(2012/10/08 19:06), Glauber Costa wrote:

It is useful to know how many charges are still left after a call to
res_counter_uncharge. While it is possible to issue a res_counter_read
after uncharge, this can be racy.

If we need, for instance, to take some action when the counters drop
down to 0, only one of the callers should see it. This is the same
semantics as the atomic variables in the kernel.

Since the current return value is void, we don't need to worry about
anything breaking due to this change: nobody relied on that, and only
users appearing from now on will be checking this value.

Signed-off-by: Glauber Costa <redacted>
CC: Michal Hocko <redacted>
CC: Johannes Weiner <redacted>
CC: Suleiman Souhlal <redacted>
CC: Kamezawa Hiroyuki <redacted>
---
  Documentation/cgroups/resource_counter.txt |  7 ++++---
  include/linux/res_counter.h                | 12 +++++++-----
  kernel/res_counter.c                       | 20 +++++++++++++-------
  3 files changed, 24 insertions(+), 15 deletions(-)

Acked-by: KAMEZAWA Hiroyuki <redacted>